The invention relates to a method of obtaining a copy protected optical record carrier carrying information in different blocks, a method of accessing such a copy protected optical record carrier and such an optical record carrier itself. Access devices for optical carriers return different results when retrieving blocks, which contain incorrect address data in the corresponding subcode fields. A copy protection key will be implemented during manufacture of an optical record carrier by modifying the subcode address information of a predetermined pattern of blocks. It is normally not possible to copy incorrect address data onto an optical record carrier, since the address data will be newly generated during the copy process. Therefore, such a key can be utilized to distinguish between an original disc and a copied or non original disc. The key is preset before manufacturing of the optical record carrier itself and can therefore be used to encrypt the data stored on the optical record carrier. Upon accessing of the data, first the key is extracted from the optical record carrier and then the data can be decrypted utilizing this key.
Legal claims defining the scope of protection, as filed with the USPTO.
1. Method of obtaining a copy protected optical record carrier carrying information in different blocks, comprising the following steps: (a) define number of subcode fields and corresponding addresses of blocks used for copy protection; (b) convert number of subcode fields and corresponding addresses selected in step (a) into a copy protection key; (c) secure information data to be recorded onto the record carrier with copy protection key obtained in step (b); (d) create a master having modified and therefore invalid subcode fields for blocks selected in step (a) and secured information data in other blocks; and (e) replicate record carrier with master created in step (d).
2. Method according to claim 1 , characterized in that said step (c) of securing the record carrier comprises the following steps: (c1) encrypt data to be recorded with said copy protection key derived in step (b) at least partially; and (c2) append extraction and decryption programme to said encrypted data derived in step (c1), wherein said extraction programme finds said blocks carrying modified subcode information and extracts said copy protection key therefrom, and said decryption programme decrypts said information data encrypted in step (c1) according to said copy protection key extracted by said extraction programme when they are executed.
3. Method according to claim 1 , characterized in that said step (c) of securing the record carrier comprises the following steps: (c1) append extraction and comparing programme to said information data, and (c2) append copy protection key to said information data, wherein said extraction programme finds said blocks carrying modified subcode information and extracts said copy protection key therefrom, and said comparing programme compares said extracted copy protection key and said appended copy protection key to be able to at least partially deny access to said information data in dependency on the correlation of said both copy protection keys when they are executed.
4. Method according to claim 1 , characterized in that said modified subcode fields are modified as to be recognized invalid by a reading device.
5. Method according to claim 1 , characterized in that said modified subcode fields are created so that they include no or invalid address information.
6. Method according to claim 1 , characterized in that said modified subcode fields are SUBCODE Q fields.
7. Method according to claim 1 , characterized in that said record carrier is a compact disc and said information is audio data together with control data and information data.
8. Method according to claim 1 , characterized in that said record carrier is a compact disc read only memory and said information is any form of digital data.
9. Method of accessing a copy protected optical record carrier carrying information in different blocks, comprising the following steps: (a) find blocks having a modified and therefore invalid corresponding subcode field; (b) extract a copy protection key from a pattern of said blocks having a modified and therefore invalid corresponding subcode field found in step (a); and (c) retrieve data from the record carrier according to the copy protection key extracted in step (b).
10. Method according to claim 9 , characterized in that said step (a) includes the finding of blocks having a modified corresponding SUBCODE Q field.
11. Method according to claim 9 , characterized in that said step (a) includes the following steps: (a1) trying to access a predetermined block based on the address defined in the SUBCODE Q field of said block by sending a respective command to an optical pickup of a disc drive to access said predetermined block; (a2) determining if said optical pickup has accessed said predetermined block by checking of the block address defined in the SUBCODE Q field or the main code data directly after the access procedure of the optical pickup; and (a3) storing all block addresses of blocks the optical pickup could not access directly.
12. Method according to claim 11 , characterized in that said step (a3) additionally comprises the step of storing all block addresses of blocks the optical pickup could access directly, and in said step (b) of extracting a copy protection key said key is extracted from a pattern of said blocks having a modified corresponding subcode field and of said blocks having no modified corresponding subcode field.
13. Method according to claim 9 , characterized in that said step (c) of retrieving data from the record carrier comprises the decryption of the retrieved data with copy protection key extracted in step (b).
14. Method according to claim 9 , characterized in that said step (c) of retrieving data from the record carrier comprises the following steps: comparison of the copy protection key extracted in step (b) and a copy protection key appended to the information carried by the record carrier; allowing at least partial or no access to said information data in dependency on the correlation of said both copy protection keys.
15. Method according to claim 9 , characterized in that said step (c) of retrieving data from the record carrier comprises the following steps: comparison of a copy protection key entered during the data retrieval with the copy protection key extracted in step (b), and allowing at least partial or no access to said information data in dependency on the correlation of said both copy protection keys.
16. Method according to claim 9 , characterized in that said steps of data retrieval are conducted with the help of software included on the record carrier.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
August 26, 1998
March 18, 2003
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